Surgical microscopes are supported by stands that either rest on the floor or are mounted on the wall or ceiling. As a result of utilization of the microscope with its functions such as X/Y displacement, zoom adjustment, and release of the brakes in the articulated arms; or because of external oscillations caused e.g. by the vibrations of passing trucks or insufficiently vibration-isolated air conditioning systems, the microscope can be caused to vibrate, resulting in a visible unsteadiness of the microscope image.
In order to eliminate a visible unsteadiness, there are solutions that are used in photographic lenses and field glasses such as those published e.g. in U.S. Pat. No. 6,226,458 B1, U.S. Pat. No. 6,191,813 B1, U.S. Pat. No. 5,940,630, U.S. Pat. No. 5,561,498, U.S. Pat. No. 5,335,032, U.S. Pat. No. 5,245,378, U.S. Pat. No. 5,243,462, U.S. Pat. No. 5,182,671, U.S. Pat. No. 5,126,561, U.S. Pat. No. 5,107,293, U.S. Pat. No. 5,101,230, U.S. Pat. No. 4,970,540, and U.S. Pat. No. 3,942,862, and in “Zeiss Information” 4 (1995) No. 6, page 24. With these known solutions, the troublesome vibration is sensed either electronically or mechanically, and an optical constituent (e.g. a lens or a prism) is then moved or adjusted in order to compensate for the vibration. This motion or adjustment occurs in regulated fashion, by means of either a motorized drive or mechanical lever forces. U.S. Pat. No. 5,731,896, U.S. Pat. No. 5,786,936, DE-A-43 42 717, and DE-A-43 42 538 also describe comparable systems for surgical microscopes. Here as well, vibrations of the system are measured so as thereby to counter-control an optical element, in this case the main objective.
The description below, especially that of disadvantages, is confined to surgical microscopes, although the invention can also be used successfully with other devices. U.S. Pat. No. 5,731,896, U.S. Pat. No. 5,786,936, DE-A-43 42 717, and DE-A-43 42 538 describe a solution for surgical microscopes in which vibrations of the system are measured. Motors that can move the main objective relative to the microscope in the X/Y plane compensate for this vibration, so that the subject image appears relatively steady in the eyepiece.
An important disadvantage with this known solution occurs because the objective's vibration is compensated for only in the X/Y plane. In the Z direction it continues to vibrate in undamped fashion. Vibrations that can no longer be compensated for by the depth of focus of the objective therefore have a severe impact on the contrast and sharpness of the subject image.
A further disadvantage is also that the entire microscope can continue to vibrate relative to the observing surgeon; in some circumstances, as a result of excessive vibration he or she can lose the exit pupil or be presented with a vignetted image.
In order to eliminate the latter disadvantage, an obvious choice is to compensate for vibrations of the entire optical system. Such solutions have been proposed, for example in U.S. Pat. No. 5,731,896, U.S. Pat. No. 5,786,936, DE-A-43 42 717, and DE-A-43 42 538.
Here motors move the entire microscope in the X/Y plane in order to compensate for vibrations, so that the subject image appears relatively steady in the eyepiece. Here again, however, no compensation is performed in the Z direction, and it is disadvantageous that the motors must move greater masses.